# linear discriminant analysi

data<-read.table("ex03a.dat")
names(data)<-c("x1","x2","y")

x<-seq(-6,10,0.1)
y<-seq(-6,10,0.1)

Xcon <- data.frame(rep(x,length(y)), rep(y, each=length(x)))
names(Xcon) <- c("x1","x2")

g <- lda( y ~ x1 + x2 , data = data)

#par(mfcol=c(2,1))

plot(data$x1,data$x2, xlim=c(-6,10), ylim=c(-6,10), type="n")
points(data$x1,data$x2,col=(data$y+1))

Z <- predict(g, Xcon)
zp <- Z$post[,1] - Z$post[,2]
contour(x,y,matrix(zp,length(x),length(y)), add=T, levels=0, labex = 0)
title("Linear Discrimant Analysis")